Whistle Detector

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1/*
2
3 This example reads audio data from an Invensense's ICS43432 I2S microphone
4
5 breakout board, and uses the input to detect whistling sounds at a particular
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7 frequency. When a whistle is detected, it's level is used to control the
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9 brightness of an LED
10
11 Circuit:
12
13 * Arduino Zero, MKRZero or MKR1000 board
14
15 * ICS43432:
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17   * GND connected GND
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19   * 3.3V connected 3.3V (Zero) or VCC (MKR1000, MKRZero)
20
21   * WS connected to pin 0 (Zero) or pin 3 (MKR1000, MKRZero)
22
23   * CLK connected to pin 1 (Zero) or pin 2 (MKR1000, MKRZero)
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25   * SD connected to pin 9 (Zero) or pin A6 (MKR1000, MKRZero)
26
27 created 30 November 2016
28
29 by Sandeep Mistry
30
31 */
32
33#include <ArduinoSound.h>
34
35// the LED pin to use as output
36
37const int ledPin = LED_BUILTIN;
38
39// sample rate for the input
40
41const int sampleRate = 8000;
42
43// size of the FFT to compute
44
45const int fftSize = 128;
46
47// size of the spectrum output, half of FFT size
48
49const int spectrumSize = fftSize / 2;
50
51// frequency of whistle to detect
52
53const int whistleFrequency = 1250;
54
55// map whistle frequency to FFT bin
56
57const int whistleBin = (whistleFrequency * fftSize / sampleRate);
58
59// array to store spectrum output
60int spectrum[spectrumSize];
61
62// create an FFT analyzer to be used with the I2S input
63
64FFTAnalyzer fftAnalyzer(fftSize);
65
66void setup() {
67
68  // setup the serial
69
70  Serial.begin(9600);
71
72  // configure the pin for output mode
73
74  pinMode(ledPin, OUTPUT);
75
76  // setup the I2S audio input for the sample rate with 32-bits per sample
77
78  if (!AudioInI2S.begin(sampleRate, 32)) {
79
80    Serial.println("Failed to initialize I2S input!");
81
82    while (1); // do nothing
83
84  }
85
86  // configure the I2S input as the input for the FFT analyzer
87
88  if (!fftAnalyzer.input(AudioInI2S)) {
89
90    Serial.println("Failed to set FFT analyzer input!");
91
92    while (1); // do nothing
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94  }
95}
96
97void loop() {
98
99  if (fftAnalyzer.available()) {
100
101    // analysis available, read in the spectrum
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103    fftAnalyzer.read(spectrum, spectrumSize);
104
105    // map the value of the whistle bin magnitude between 0 and 255
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107    int ledValue = map(spectrum[whistleBin], 50000, 60000, 0, 255);
108
109    // cap the values
110
111    if (ledValue < 0) {
112
113      ledValue = 0;
114
115    } else if (ledValue > 255) {
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117      ledValue = 255;
118
119    }
120
121    // set LED brightness based on whistle bin magnitude
122
123    analogWrite(ledPin, ledValue);
124
125  }
126}